The present invention relates to a hydraulic control apparatus for the hydraulic system of hydraulic actuators, such as hydraulic cylinders.
In these days, the control of hydraulic systems in vehicles including agricultural and construction machines has a tendency to be carried out by using solenoid-operated switching valves in order to meet requirements for higher efficiency and higher accuracy of operation, for remote-controlled operation and for the compounding of operations. However, solenoid switching valves heretofore in use are large-sized, expensive and unreliable, and moreover they can hardly be applied to multi-control.